XI'AN, CHINA - AUGUST 11: Firefighters and policemen work at the expressway accident scene on August 11, 2017 in Xi An, Shaanxi Province of China. At least 36 people were killed and 13 others injured in the expressway accident occurred on Thursday night. The accident occurred at around 11:34 p.m. when a coach hit the wall of the Qinling tunnel of the Xi'an-Hanzhong Expressway. The injured have been sent to hospitals. (Photo by VCG)

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XI'AN, CHINA - AUGUST 11: Firefighters and policemen work at the expressway accident scene on August 11, 2017 in Xi An, Shaanxi Province of China. At least 36 people were killed and 13 others injured in the expressway accident occurred on Thursday night. The accident occurred at around 11:34 p.m. when a coach hit the wall of the Qinling tunnel of the Xi'an-Hanzhong Expressway. The injured have been sent to hospitals. (Photo by VCG)

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XI'AN, CHINA - AUGUST 11: The expressway accident scene is seen on August 11, 2017 in Xi An, Shaanxi Province of China. At least 36 people were killed and 13 others injured in the expressway accident occurred on Thursday night. The accident occurred at around 11:34 p.m. when a coach hit the wall of the Qinling tunnel of the Xi'an-Hanzhong Expressway. The injured have been sent to hospitals. (Photo by VCG)

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XI'AN, CHINA - AUGUST 11: Firefighters and policemen work at the expressway accident scene on August 11, 2017 in Xi An, Shaanxi Province of China. At least 36 people were killed and 13 others injured in the expressway accident occurred on Thursday night. The accident occurred at around 11:34 p.m. when a coach hit the wall of the Qinling tunnel of the Xi'an-Hanzhong Expressway. The injured have been sent to hospitals. (Photo by VCG)

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XI'AN, CHINA - AUGUST 11: Firefighters and policemen work at the expressway accident scene on August 11, 2017 in Xi An, Shaanxi Province of China. At least 36 people were killed and 13 others injured in the expressway accident occurred on Thursday night. The accident occurred at around 11:34 p.m. when a coach hit the wall of the Qinling tunnel of the Xi'an-Hanzhong Expressway. The injured have been sent to hospitals. (Photo by VCG)

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XI'AN, CHINA - AUGUST 11: Firefighters and policemen work at the expressway accident scene on August 11, 2017 in Xi An, Shaanxi Province of China. At least 36 people were killed and 13 others injured in the expressway accident occurred on Thursday night. The accident occurred at around 11:34 p.m. when a coach hit the wall of the Qinling tunnel of the Xi'an-Hanzhong Expressway. The injured have been sent to hospitals. (Photo by VCG)

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XI'AN, CHINA - AUGUST 11: Firefighters and policemen work at the expressway accident scene on August 11, 2017 in Xi An, Shaanxi Province of China. At least 36 people were killed and 13 others injured in the expressway accident occurred on Thursday night. The accident occurred at around 11:34 p.m. when a coach hit the wall of the Qinling tunnel of the Xi'an-Hanzhong Expressway. The injured have been sent to hospitals. (Photo by VCG)